The present invention relates to a composition comprising an untreated or treated culture of lactic acid bacteria mixed with a yeast, and to a functional food comprising said composition.
Fermented foods comprising lactic acid bacteria have been expected to prevent adult""s diseases and promote health. Such foods are typified by fermented milk (yoghurt); in addition, lactic acid bacteria beverage and sour milk have been well popularized.
Many reports have been made on physiological activities of lactic acid bacteria and fermented foods; therefore, they are expected to be utilized as healthy foods.
In most of brewed foods including sake, bean paste (miso) and soybean sauce, it has been known that unique flavor and taste and components are generated by symbiotic or antagonistic actions between several microorganisms co-cultured in media. However, few of lactic acid bacteria or fermented foods thereof are produced by so-called cocultivation and physiological activities of the bacteria have not been known.
It is an object of the present invention to provide a composition comprising an untreated or treated culture of lactic acid bacteria mixed with a yeast, and to a functional food comprising said composition.
The present inventors have made great efforts to solve the above mentioned problem and found that a culture of lactic acid bacteria mixed with a yeast or a treated material thereof exhibits various functions. Thus, the present invention has been completed.
Accordingly, the present invention provides a composition comprising an untreated or treated culture of at least three lactic acid bacteria selected from the group consisting of Lactobacillus delbrueckii, Lactobacillus acidophilus, Lactobacillus plantarum, Lactobacillus fermentum, Lactobacillus casei, Lactobacillus rhamnosus, Lactococcus lactis and Streptococcus thermophilus, which are mixed with Saccharomyces cerevisiae. The mixed microorganisms used in the present invention include Lactobacillus delbrueckii, Lactobacillus casei, Lactococcus lactis and Saccharomyces cerevisiae; Lactobacillus acidophilus, Lactobacillus rhamnosus, Lactococcus lactis and Saccharomyces cerevisiae; Lactobacillus plantarum, Lactobacillus casei, Streptococcus thermophilus and Saccharomyces cerevisiae; as well as Lactobacillus fermentum, Lactobacillus rhamnosus, Streptococcus thermophilus and Saccharomyces cerevisiae. 
Further, the present invention provides a functional food comprising said composition. This specification includes part or all of the contents as disclosed in the specification and/or drawings of Japanese Patent Application No. JP 98/24892, which is a priority document of the present application.
Hereinafter the present invention will be described in detail.
The composition of the present invention comprises a culture obtained by culturing (co-cultivating) a mixed microorganism comprising lactic acid bacteria and yeast, or a treated material thereof.
Lactic acid bacteria include those belonging to the genus Lactobacillus, Lactococcus or Streptococcus, such as Lactobacillus delbrueckii, Lactobacillus acidophilus, Lactobacillus plantarum, Lactobacillus fermentum, Lactobacillus casei, Lactobacillus rhamnosus, Lactococcus lactis and Streptococcus thermophilus. 
Yeast includes Saccharomyces cerevisiae. 
Said microorganisms used may be generally commercially available; they are not limited to particular strains of said microorganisms provided that an untreated or treated co-culture of these microorganisms can be utilized as functional foods. For example, lactic acid bacteria belonging to the genus Lactobacillus include Lactobacillus delbrueckii strain ALAL007, Lactobacillus acidophilus strain ALAL005, Lactobacillus plantarum strain ALAL006, Lactobacillus fermentum strains ALAL001 and JCM1173, Lactobacillus casei strains ALAL002, ALAL003 and JCM1053, and Lactobacillus rhamnosus strains ALAL004, ALAL010 and JCM1136; lactic acid bacteria belonging to the genus Lactococcus include Lactococcus lactis subsp. hordniae strains ALAL008 and ALAL009; lactic acid bacteria belonging to the genus Streptococcus include Streptococcus thermophilus strains ALAL011 and ALAL012; and yeast includes for example Saccharomyces cerevisiae strains JCM1499, ALAY001, ALAY002, ALAY003 and ALAY004.
Saccharomyces cerevisiae strain ALAY001, Lactobacillus fermentum strain ALAL001, Lactobacillus casei strain ALAL003, and Lactobacillus rhamnosus strain ALAL004 have been deposited under the Budapest Treaty on Nov. 28, 1997 with National Institute of Bioscience and Human-Technology, Agency of Industrial Science and Technology (1-3 Higashi 1-chome, Tsukuba-shi, Ibaraki, 305-0046, Japan) under Accession Nos. FERM BP-6626, 6627, 6628 and 6629, respectively.
According to the present invention, the mixed microorganism consists of at least three arbitrarily selected lactic acid bacteria and one yeast. For example, the combination of the microorganisms may be any of the group A to D as set forth in Table 1.
Any of the Groups A to D may be used alone (4 strains of microorganisms); or two or more groups may be combined. If microorganisms of the same species are included in two or more groups to be combined and used (for example, L. casei and S. cerevisiae are overlapped when Groups A and C are to be combined), different strains of the same species should be used.
The composition of the present invention may be obtained by cultivating the mixed microorganism comprising lactic acid bacteria and yeast in a medium containing hot water extract of soybean.
The medium comprises hot water extract of soybean. After mixing 1xc3x97105 to 1xc3x97106 of each of lactic acid bacteria per ml with 1xc3x97104 to 1xc3x97106 of a yeast per ml, the mixed microorganism is inoculated in the medium and cultivated at 20 to 37xc2x0 C. for 4 to 10 days.
When a plurality of microorganisms from different Groups are to be combined, each of the Groups to be combined is cultivated under the above described conditions and then mixed with each other followed by cultivating under the above described conditions.
After cultivation, the culture is boiled at 80xc2x0 C. to sterilize and recovered.
The composition of the present invention may be obtained by freezexe2x80x94 or spray-drying the culture. Alternatively, the culture may be treated by filtration or centrifugation or otherwise to separate the supernatant from the cells. In this case, the supernatant and cells may also be freezexe2x80x94 or spray-dried to prepare each a composition of the present invention.
The composition of the present invention may be in any form and can be processed into a liquid, solid, granule or the like. A granular form is preferred since it may be conveniently handled.
When processed into a granule, it is included in a polysaccharide such as cyclodextrin.
The composition of the present invention obtained in the above manner have various activities and, therefore, may be used as a healthy food having some function (functional food). Such activities include, for example, liver and kidney function improving activity, anti-mutagenic activity, tumor cell growth inhibiting activity, and enteric bacterial flora improving activity.
When in a granular form as usual, the composition of the present invention may be used as a functional food by eating in the granular form or adding an appropriate amount thereof to a food.
Foods include, but not limited to, for example, cakes such as jellies and candies, beverages such as juices, teas and nutritional drinks, and rice.
The amount and rate of the composition of the present invention added to a food may be adjusted as appropriate depending upon preference and usually 0.1 to 1% by weight per food.